Retarded relay



S 1946- L. w. DROEL. I 2,407,633

RETARDED RELAY Filed July 15, 1943 INVENTOR. LOUIS W. DROEL ATTORNEYPatented Sept. 17, 1946 UNITED RETARDED RELAY Louis W. Droel, Qak Park,Ill., assignor to Automatic Electric Laboratories, Inc., Chicago, 111.,a

corporation of Delaware Application July 15, 1943, Serial No. 494,769

Claims. 1

Thi invention, relates in general to electromagnetic relays and moreparticularly to relays of the retarded type having pivotally mountedarmatures which are retarded. in both their operating and releasingoperations.

An electromagnetic relay of the conventional type comprises a fieldstructure, a core provided with an operating winding, a pivotal armaturemounted. on the field structure, and contact springs. operativelyassociated with the operating arm of the armature.

It is the object of the present invention to provide an improvedretarding means for the relay armature which both frictionally retardsthe movements of the armature and which also eliminates vibration of thearmature mass from an external cause, such as is encountered when therelay is mounted in a tank, airplane, or other vibratory machinery.

Relays having armatures of the pivot pin type have been extensively usedin telephone systems and have proved very satisfactory. However, due tomanufacturing tolerances between the pivot pin and the bearing holes forthe pivot pin, it has been found that relays of this type, whensubjected to constant vibration from an external source, are subject to.stresses not present in the normal use of these relays. Tests. haveshown that the vibration caused excessive wear on either the bearingsurfaces for the pivot pin or upon the pivot pin itself, therebyinterfering with the nor-- mal operating characteristics. of the relay.The analysis of this excessive wear shows that it results from at leasttwo difierent typesv of motions.

The armature exerts a turnim proportional to its mass and the rate andthe directions of the vibrations. This tends to produce oscillations ofthe armature transverse to the axis of the pivot pin at a ratecorresponding to the vibration rate.

If the vibration are in a plane which includes a pivot pin and thecenter of mass of the armature, a force is exerted which tends to makethe pivot pin chatter in the bearing surface at a rate proportional tothe vibration rate.

A feature of the invention is to retard the op erating and releasingmovement of the armature and to eliminate the above mentioned motions ofthe armature produced by external vibrations of a relay by tensioning aspring against the operating arm of the armature at right angles to itsmovement. The tension applied by the spring to the operating arm has twoeffects: one is to frictionally retard the operating and releasingmovements of the armature in accordance with the amount of tension inthe spring; and the other is to exert a twisting action or torque on thearmature bearing pin at its associated bearing holes in the relay yoke.This twisting action maintains the pivot pin in constant engagement withthe bearing surfaces of the bearing hole and elimihates theobjectionable vibratory motions of the armature from external causes.

In addition, the retarding spring has an inclined surface, or offset,over which the operating arm of the armature must move to therebyincrease the frictional pressure to retard the operation of the armaturein its operating stroke in its initial movement.

Other objects and features of the present invention will be apparent byreference to the fol lowing specificationtaken in connection with theaccompanying drawing in which:

Fig. 1 is a partially perspective view of the relay;

Fig. 2 is aside view of the relay;

Fig. 3 is another side view of the relay; and

Fig. 4 is a cross-section of the relay taken on the lines AA in Fig. 3.

Referring now to the drawing, the electromagnetic relay shown comprisesa field structure including a core 6 provided with a winding 4, asubstantially L-shaped magnetic heel piece I 9 secured to the core 55 bymeans of a screw 35 and a movable magnetic armature I 5 having an operating, arm 35 and a bushing The armature I5 is pivotally mounted upon theouter end of the heel piece IQ for cooperation with the core 6.

The armature it carries a pair of upwardly extending ears 35 providedwith aligned holes therein in which the pivot pin it is rigidly securedto the cars 36 of the armature it.

A relay yoke 2% has upturned ears 372 and is provided with bearing holes38 to provide the bearing surfaces for the pivot pin it. The yoke 25! isprovided with a slot and by mean of the clamping washer and the maclnnescrew 25 is adjustably secured to the heel piece iii. It is thecustomary procedure to assemble the armature and yoke together and tomount the armature in operating relation to the core of the relay bymeans of the clamping washer i3 and the machine screw 26. The springassembly comprises an armature backstop l3 which is placed against theheel piece I9, the insulators 88, the spring contacts I, 2, 5, and 5,the metal plate 3, all of which are provided with holes through whichthe ma chine screws 2'5 extend through to threaded holes (not shown) inthe heel piece for securing this spring assembly to the heel piece inthe position shown in Fig. 3.

A retarding spring assembly is mounted on the heel piece 19 between therelay yoke 20 and the spring assembly. This assembly comprises a springmounting bracket 2! secured to the heel piece by means of the screw 29and the shakeproof Washer 3!. The retarding spring I1, is mounted on theupper portion of the bracket 2| by means of the screw 28, the washer land the shake-proof lockwasher H. The spring I! is mounted at rightangles to the movement of the armature arm 35, and the spring IT istensioned against the operating arm for two purposes; one is .to cause atwisting action, of the pivot pin in the bearing holes of the relay yoketo prevent chattering or motion of the armature from external vibratorycauses; the other is to provide frictional resistances to the operatingarm so as to retard the operating movement of the arm 35. It will benoted in Fig. 4 that the spring I! has an offset 34 which is positionedadjacent to the operating arm so that on the initial movement of the arm35 the inclined portion of this offset is encountered thereby increasingthe frictional resistance on the initial movement of the arm when thearm begins to move over this inclined surface. Due to this inclinedsurface and the movement of the arm the tension against the arm 35 isgradually increased to have a retardin effect on the operating stroke ofthe armature. Once the armature is operated, however, and the armaturearm has moved over this inclined surface (or form) the force of thisspring (l1) tending to maintain the armature in its original position isremoved. But with the relay armature in its operated position thefriction of this spring against the armature, then tends to retard itsrelease.

The relay is of the well-known horizontal type which has been usedextensively in telephone systems and the improvement consists of theaddition of the spring H which retards the operating and restoringstrokes of the armature during controlled operations, due to thefrictional pressure, and which also prevents the armature fromoscillating or chattering due to external vibratory causes.

It is well-known that in mass production of a large number of partswhich are to be assembled together, manufacturing tolerances withincertain limits are resorted to in order to speed up production to allowinterchangeable assembly and to reduce the cost of manufacturing suchparts. For example, since relay parts are manu" factured in largenumbers, manufacturing tolerances are allowed on both the pivot pin isand the pivot pin bearing holes 38 in the ears 3?. It has been foundthat in manufacturing the pivot pin l4 it may be oversized or undersizedfrom the desired diameter and that the bearing holes 38 may be alsooversized or undersized from the desired diameter. seen that a minimumdiameter pivot pin may be assembled in a maximum diameter bearing holeof the relay yoke. Consequently, there may be considerable play betweenthe pivot pin and the bearing hole. sembled with a pivot pin of minimumdiameter mounted in a bearing hole having a maximum diameter, and therelay is mounted on an object subject .to vibrations, such as may beencountered in an airplane, tank, automobile, or other vibratorymachinery, the vibration of the armature will cause a gradual wearing ofthe pivot pin or peening of the bearing hole or both, and therebygradually increasing the play between these parts to such an extent thatthe operating characteristics of the relay will be materially affected.

According to the present invention the pressure applied at right anglesto the operating stroke of the operating arm 35; as indicated by thearrow C, causes the armature to take up the play between the right-handear 35 of the armature, the washer l0, and the right-hand ear 3'! of theyoke as shown in Fig. 1. After this play is taken up the pressure of thespring I! against arm causes the armature I 5 to be twisted in thedirec- In view of the above, it can be In the event that a relay isastions indicated by arrows D and E with the righthand portion of thepivot pin l4 pressing against the back surface of the bearing hole 38 inthe right-hand ear 3! while the left-hand portion of the pivot pinpresses against the front surface of the bearing hole in the left-handear 3! of the yoke 20. When this latter play is taken up due to thetension of the spring I! against arm 35 there is an additional twistingaction of the armature as indicated by arrows F-F due to the location atwhich the pressure is applied to the arm 35. This cumulative twistingaction, although insufiicient to materially affect the normal operationof the relay is sumcient to take up the play which may occur as a resultof manufacturing tolerances and is sufficient to prevent undesiredmovements of the armature when such a relay is mounted on an objectsubject to vibration.

It will also be noted that the arm 35 is engaged by spring I! and ismoved across the surfaces of spring I! during its operating andreleasing strokes. The movement of the arm 35 across the surface of thespring I! is retarded by frictional pressure in accordance with theamount of tension in spring l1. As seen in Fig. 4, the arm 35 isnormally engaged by spring I! at the lowermost part, or the beginning,of the inclined surface, or offset 35. The purpose of the offset 34 isto increase the frictional resistance on the initial movement of arm 35so as to retard the initial movement of the armature to make it somewhatslow-to-operate and to assist in preventing it from operatingaccidentally when the relay is subjected to vibration or shock. It istherefore necessary for the relay to build up enough magnetic flux toovercome the increased frictional resistance offered by the offset 34before the armature is initially moved from its normal position, therebyeffecting a delay in the operation of said armature. As the arm 35 movesupward, as viewed in Fig. 4, the spring I! is gradually depressedthereby increasing the frictional resistance between arm 35 and springI1. After the arm 35 has moved over the top of the offset 34, thearmature has by this time moved closer to the core, thereby increasingthe magnetic pull so that the frictional pressure, which has decreasedas the arm moved over the offset, has very little effect on the furthermovement of the armature.

It should also be noted that the tension of spring I! also has aretarding effect on the armature during its release stroke to normalposition, thereby rendering the relay somewhat slow-torelease. When themagnetic flux gradually dies down, the frictional pressure of spring I!against arm 35 delays, somewhat, the time at which the armature startsits restoring stroke. In addition, as the armature of arm 35 starts theslide down the offset 34 during its release stroke, the frictionalpressure rapidly decreases and a restoring component force is introducedby the upward tension of the sloping surface of the offset 34 at thiscritical point with the result that the releasing movement of thearmature is speeded up. It is at this critical point and during thespeeded up release of armature l5 that the make springs I and 3 arequickly separated. This quick separation of springs I and 3 is desirableto prevent arcing or burning of the spring contacts. Thus, in additionto initially retarding the restoring stroke of the armature I5, thespring 11 with its offset 34 speeds up the release stroke at thecritical point in the armature movement where certain of the springscontrol circuits.

Having described the invention, what is considered new and as desired tohave protected by new Letters Patent is specifically pointed out in thefollowing claims.

What is claimed is:

1. In a non-locking relay, an L-shaped heelpiece, a magnet mounted onsaid heel-piece, an L-shaped armature comprising an operating arm and apivot pin, a yoke having bearing holes thru which said pivot pinextends, means for securing said yoke tosaid heel-piece therebypivotally securing said armature to said heel-piece to complete themagnetic circuit including the core of said magnet, said heel-piece andsaid armature, a spring mounted on said heel-piece and normallytensioned against said operating arm to create a torque or twistingaction between said armature bearing pin and the bearing holes in saidyoke thereby preventing vibration of said armature from external causeswhile in normal position, and said spring also friotionally retardingthe operating and releasing movements of said armature withoutmaintaining or looking said armature in any operated position to makesaid armature somewhat slower to operate and to release.

2. In a non-locking relay, an L-shaped heelpiece, a magnet mounted onsaid heel-piece, an L-shaped armature comprising an operating arm and apivot pin, a yoke having bearing holes thru which said pivot pinextends, means for securing said yoke to said heel-piece therebypivotally securing said armature to said heel-piece to complete themagnetic circuit including the core of said magnet, said heel-piece andsaid armature,

a spring mounted on said heel-piece and normally tensioned against saidoperating arm to create a torque, or twisting action, between saidarmature bearing pin and the bearing holes in said yoke therebypreventing vibration of said arma ture from external causes while innormal position, the force exerted on said arm by said spring causingrotation of said armature in two planes at right angles to each otheruntil all play between said pivot pin and bearing holes is taken up andsaid pivot pin is tensionally held against the bearing surfaces of saidbearing holes as a result of the force applied, said spring havingsufiicient tension to frictionally retard the operation of said armatureduring its operating stroke to thereby make said armature somewhatslower to operate, the shape of said spring and the tension thereofbeing insuiiicient to maintain or lock said armature in operatedposition, and said spring tension being sufiicient to retard thereleasing movement of said armature during its release stroke to therebymake said armature somewhat slower to release.

3. In a non-locking relay, an L-shaped heelpiece, a magnet mounted onsaid heel-piece, an L-shaped armature comprising an operating arm and apivot pin, a yoke having bearing holes thru which said pivot pinextends, means for securing said yoke to said heel-piece therebypivotally securing said armature to said heel-piece to com- If plete themagnetic circuit including the core of said magnet, said heel-piece andsaid armature, a spring mounted on said heel-piece and normallytensioned against said operating arm to create a torque or twistingaction between said armature bearing pin and the bearing holes in saidyoke thereby preventing vibration of said armature from external causeswhile in normal position, the force exerted on said arm by said springcausing rotation of said armature in two planes at right angles to eachother until all play between said pivot pin and bearing holes is takenup and said pivot pin is tensionally held against the bearing surfacesof said bearing holes as a result of the force applied, and said springalso frictionally retarding the operating and releasing movements ofsaid armature without maintaining said armature locked in any operatedposition to make said armature somewhat slower to operate and torelease.

4. In a non-locking relay, an L-shaped heelpiece, a magnet mounted onsaid heel-piece, an

L-shaped armature comprising an operating arm and a pivot pin, a yokehaving bearing holes thru which said pivot pin extends, means forsecuring said yoke to said heel-piece thereby pivotally securing saidarmature to said heel-piece to complete the magnetic circuit includingthe core of said magnet, said heel-piece and said armature, a springmounted on said heel-piece and normally tensioned against said operatingarm, the spring pressure applied by said spring to said arm being in aplane parallel to the plane of the pivot pin and causes, first, theendwise movement of armature in a plane parallel to pivot pin untilstopped by the yoke, and second, the twisting of said armature in twoplanes at right angles to each other until all play between said pivotpin and bearing holes is taken up and whereby said pivot pin istensionally held against the bearing surfaces of said bearing holes as aresult of the cumulating twisting force applied in said two planes toprevent vibration of said armature while in normal position, said springhaving sufficient tension to frictionally retard the operation of saidarmature during its operating stroke to thereby make said armaturesomewhat slower to operate, the shape of said spring and the tensionthereof being insufiicient to maintain or look said armature in operatedposition, and said spring tension being sufilcient to retard thereleasing movement of said armature during its release stroke to therebymake said armature somewhat slower to release.

5. In a non-locking relay, an L-shaped heelpiece, a magnet mounted onsaid heel-piece, an L-shaped armature comprising an operating arm and apivot pin, a yoke having bearing holes thru which said pivot pinextends, means for securing said yoke to said heel-piece therebypivotally securing said armature to said heel-piece to complete themagnetic circuit including the core of said magnet, said heel-piece andsaid armature, a spring mounted on said heel-piece and normallytensioned against said operating arm, the spring pressure applied bysaid spring to said arm being in a plane parallel to the plane of thepivot pin and causes, first, the endwise movement of armature in a planeparallel to pivot pin until stopped by the yoke, and second, thetwisting of said armature in two planes at right angles to each otheruntil all play between said pivot pin and bearing holes is taken up andwhereby said pivot pin is tensionally held against the bearing surfacesof said bearing holes as a result of the oumulating twisting forceapplied in said two planes to prevent vibration of said armature whilein normal position, and said spring also frictionally retarding theoperating and releasing movements of said armature without looking saidarmature in any operated position to make said armature somewhat slowerto operate and to release.

LOUIS W. DROEL.

